Getting subprocess.call() output into a string?

[David]

On Tue, Apr 15, 2008 at 10:36 PM, Tobiah <toby at tobiah.org> wrote:
> I am not sure how to capture the output of a command
>  using subprocess without creating a temp file.  I was
>  trying this:
>
>  import StringIO
>  import subprocess
>
>  file = StringIO.StringIO()
>
>  subprocess.call("ls", stdout = file)
>
>  Traceback (most recent call last):
>   File "<stdin>", line 6, in ?
>   File "/usr/local/lib/python2.4/subprocess.py", line 413, in call
>     return Popen(*args, **kwargs).wait()
>   File "/usr/local/lib/python2.4/subprocess.py", line 534, in __init__
>     (p2cread, p2cwrite,
>   File "/usr/local/lib/python2.4/subprocess.py", line 840, in _get_handles
>     c2pwrite = stdout.fileno()
>  AttributeError: StringIO instance has no attribute 'fileno'
>
>  So how do I get the output into a string?
>
>  I thought that the idea of StringIO was that it could be
>  used where a file was expected.
>

For basic file-like read and write. But it won't provide a file handle
since there is no 'real' file. Also, from 2.3.9 File Objects:
"File-like objects which do not have a real file descriptor should not
provide this method!"

You should use the PIPE subprocess argument to capture output. From
the tutorial:

6.8.3.1 Replacing /bin/sh shell backquote
output=`mycmd myarg`
==>
output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]